Display racks for merchandising and other display purposes having shelves that are vertically adjustable along the corner posts are well-known in the art. Vertically adjustable shelves provide flexibility in the display of different sized articles, allowing merchandisers to use the same display rack for a variety of articles.
Early designs of adjustable display racks employed set screws or bolts to connect the corner posts and shelves. Threaded bores or apertures were formed in either the shelf or corner posts, or both, and the bolts or screws were tightened within the threaded bores to secure the shelves in place at spaced locations along the corner posts. Although this design provides for adjustment of the shelves vertically along the corner posts, an inordinate amount of time is required to remove all of the bolts connecting each shelf to a corner post and then reposition them to other locations along the corner posts. In addition, the threaded connections are subject to being over or under tightened, and as a result, the threads formed in either the bolt or threaded bores in the shelf or corner post can become worn.
In an effort to lessen the time required to adjust the location of shelves along the corner posts of a display rack, and to provide a connection between the corner posts and shelves that is less susceptible to wear, corner post-shelf connections employing a wedge lock element have been developed, as shown for example in U.S. Pat. Nos. 3,424,111 and 3,343,685. In designs of this type, a sleeve is formed in each corner of the shelf structure, which is adapted to receive a corner post. A wedge-shaped locking element or insert is adapted to mount at desired vertical locations along each of the corner posts before the shelves are moved into place. A shelf is releasably mounted to the corner posts by moving the sleeves of the shelf vertically downwardly along the corner posts and into contact with the wedge-shaped inserts. The insert becomes wedged between the sleeve and corner post preventing further downward movement of the shelf there along. Adjustment of the location of the shelf is accomplished by lifting vertically upwardly on the shelf so that the sleeves disengage the inserts, and then placing the inserts at another desired location along the corner posts.
The wedge-type connections between the shelves and corner posts of known display racks have proved to be both durable and quickly adjustable for disassembly of the display rack or repositioning of the shelves. Nevertheless, certain disadvantages are present in the construction of the wedge-shaped inserts and in their connection to the corner posts. For example, in U.S. Pat. No. 3,424,111, the wedge-shaped inserts are formed in two separate pieces which are connected to one another by a spring clip. A second spring clip is required to locate and mount the assembled wedge-shaped inserts in the proper positions along the corner posts in preparation for receiving the shelves. This design increases the number of pieces required for assembly of the inserts, and for mounting them to the corner posts, which adds to manufacturing costs and increases the difficulty of initially mounting the shelves and then moving them from one position along the corner posts to another.
In U.S. Pat. No. 3,664,274, a V-shaped wedge lock element is utilized having a tongue protrusion extending from the inner surface of one face of the wedge lock element, which hooks into a slot on the corner post, to prevent the wedge lock from falling off of the corner post and to locate the height of the shelving on the corner post. U.S. Pat. No. 4,593,826 describes a V-shaped wedge lock element of a two-piece construction interconnected by a tongue and groove arrangement. Each face of the two-piece construction includes an extending projection that engages with detents or dimples on the side faces of the square corner posts. Each of the two pieces have flanges at the ends of the perpendicular walls that extend around the corners of the corner posts, such that a portion of the wedge lock is in contact with all four sides of the square corner post, serving to keep the wedge lock from falling off of the corner post. U.S. Pat. Nos. 4,754,712 and 4,852,501 describe V-shaped wedge lock elements having a protrusion in the corner of the wedge lock element that fits into one of a plurality of notches on the corner edge of the corner post. The '712 and '501 Patents also include retaining flanges to prevent the wedge lock element from falling off of the corner post.